NEW YORK >> Justify led all the way to win the Belmont Stakes by 13/4 lengths on Saturday and become horse racing’s 13th Triple Crown champion and second in four years.

The chestnut colt became the second undefeated horse to sweep the Kentucky Derby, Preakness and Belmont, improving to 6-0 in a racing career that began on Feb. 18. Seattle Slew was unbeaten when he won the Triple Crown in 1977.

Sent off as the 4-5 favorite, Justify went to the lead out of the starting gate and led nine rivals around the track’s sweeping turns. He burnished his reputation by defeating nine rivals, the most faced by any Triple Crown champion.

Bob Baffert became the second trainer to win the Triple Crown twice. He did so with American Pharoah in 2015, ending a 37-year drought. James “Sunny Jim” Fitzsimmons guided Gallant Fox in 1930 and Omaha in 1935.

Justify’s victory gives racing its second Triple Crown winner of the decade. The last time there were two Triple Crown champions in the same decade was the 1970s, which produced Secretariat, Seattle Slew and Affirmed.

Justify achieved one of the sports’ toughest feats 45 years to the day that Secretariat won the Belmont by a record 31 lengths.

The powerful colt with the blaze running the length of his face showed no signs that the rigors of running a compressed schedule had gotten to him. He won the Kentucky Derby by 2½ lengths and then survived a half-length victory in the Preakness, both on sloppy tracks.

On a fast, dry track, Justify was just as good in his third race in five weeks at his third different track.

He ran the longest race of the series in 2:28.18 and paid $3.60, $3.50 and $2.80.

“This horse ran a tremendous race, he’s so gifted,” said Mike Smith, who at 52 is the oldest jockey to win the Triple Crown. “He’s sent from heaven. I tell you, it’s just amazing. I can’t describe the emotions that’s going through my body right now.”

Baffert had fretted after Justify drew the No. 1 post, a spot he detests for his horses. But Smith turned it into an advantage, gunning Justify to the lead and defying any horse to challenge.

“Did you see him in the gate, he’s standing so still,” Smith said. “I thought maybe he’s not going to break today.”

Restoring Hope, also trained by Baffert, ran interference for the champion while traveling second and deterring any threats by forcing them to go extremely wide. Nobody did.

Smith got the big colt into a relaxed rhythm under a moderate pace heading into the backstretch, and he had an easy trip from there.

There were mild bids turning for home. Vino Rosso made the most serious move to get within a length but never threatened. Justify pulled away down the 1,097-yard stretch in front of a grandstand packed with screaming fans with only 24-1 shot Gronkowski picking up the chase down the lane.

Gronkowski, named for and partly owned by New England Patriots tight end Rob Gronkowski, returned $13.80 and $7.